It should work to do it this way:

my @connection;
foreach (@server_list) {
    my $ssh = Net::SSH::Perl->new($_) or next;
    push @connection, $ssh;
}

foreach my $ssh (@connection) {
    # ...
}
[download]

Alternatively, if this isn't simultaneous enough, you might want to look at fork or modules like Parallel::ForkManager.

Makeshifts last the longest.